AS IF news of the royal baby wasn’t enough to steal her thunder, Princess Eugenie has suffered a further insult — Instagram account @buckinghamroyal has mistaken her for her sister while spruiking wedding souvenirs.

In a post on its Instagram page, prominent royal fan account @buckinghamroyal grandly announced the sale of commemorative mugs marking last Friday’s nuptials of Princess Eugenie and Jack Brooksbank.

The post informed followers that the limited edition mugs were available “only ’til Saturday” and could be purchased with the click of a button.

There was only one thing — the caption mistakenly referred to Eugenie’s older sister, Princess Beatrice.

“This exclusive mug issued in commemoration of the wedding of HRH Princess Beatrice of York and Mr Jack Brooksbank is now available for purchase by following the link in the description,” the caption said.

The post was swiftly deleted.Source:Supplied

Princess Eugenie on her big day.Source:AP

Princess Beatrice is the older sister of Eugenie and acted as maid of honour on her big day at Windsor Castle.

The post was swiftly deleted from the Palace’s Instagram account and will no doubt have caused numerous red faces.

However the gaffe isn’t as embarrassing as it seems on face value as @buckinghamroyal appears to be operated by fans rather than an official account — but it’s still pretty awkward when even royal supporters can’t get it right.

The fan account mistakenly referred to Princess Beatrice, pictured with her mum Sarah Ferguson at the royal wedding.Source:Getty Images

It has allegedly been a trying few days for Princess Eugenie, who was reportedly upset that Prince Harry and Meghan Markle broke their baby news to the other members of the royal family during the wedding reception.

Eugenie’s mother Sarah, the Duchess of York, was said to be furious that the Duke and Duchess of Sussex had broken an unwritten rule of sharing big news at a wedding, taking attention away from the bride.

Eugenie was reportedly upset over Harry and Meghan’s decision to tell the royals about their baby news on the day of the wedding.Source:AFP

In a pointed tweet just 40 minutes after Prince Harry and Meghan’s pregnancy news was announced, Fergie congratulated her daughter on her wedding.

As the news of the new royal baby swept the world, Ferguson — on what was also her 59th birthday — gushed that she was “so proud of Eugenie and Jack” after the lavish ceremony that saw 850 A-listers flock to Windsor.

The Duchess of York tweeted out the congratulatory message barely 40 minutes after Kensington Palace shared the baby news.